The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A national security threat is posed from illicit radioactive materials being released into a populated area using radiological dispersive devices (RDD) or “dirty bombs”. Many of these dispersive devices employ conventional explosives as their primary propellant.
Consequently, it is desirable to intercept these devices prior to a planned detonation or release. Often times, interception can be achieved through the detection of radioactive substances that are typically associated with such devices, even when such radioactive substances are concealed in containers, such as shipping containers, vehicles, luggage, parcels and the like.
In some cases, it is desirable to quickly evaluate an area that has been exposed to a release of radioactive material. For example, it can be useful to determine the geographical extent of the contamination and whether additional spreading has occurred or may occur. Information garnered from such detection and/or evaluation may prove valuable in assessing the initial risks, quelling fear or panic, and/or permitting timely evacuation of an area, closure of building ventilation systems, sheltering, or other actions directed to lessen the effects of the event. Still further, during cleanup, it can also be useful to continuously reassess the distribution of radioactivity, which may vary in response to local circumstances, such as weather conditions.
Energized portable radiation-producing equipment, such as battery-powered x-ray tubes, can also be hidden in vehicles and used to significantly expose the public as they drive by or sit in a strategic location. Detection of such events while they are occurring would be useful in preventing the exposure of large number of individuals and in capturing the perpetrators. Detection of the path of such vehicles following this type of terrorist event is invaluable for estimating doses delivered to individuals so that they may be appropriately advised and managed medically, as well as for the purposes of garnering information that can be useful for bringing the terrorists to justice.
The illegal movement of special nuclear materials (SNM) needed to make nuclear weapons, such as uranium and plutonium, remains an unsolved detection problem. Similar in nature to the radiological dispersive device (RDD) problem, early detection can prevent undesirable events and assist in the identification of terrorists. Nuclear weapons use would also result in the widespread dispersion of radioactive materials, and the attendant radiation detection problems associated with it.
Widespread networks of radiation detection devices in cities, agricultural districts, strategic areas, along international borders (within the U.S. and around states from which illicit nuclear materials may be anticipated to be leaving), and around nuclear power and nuclear weapons facilities are highly desirable.
Additional needs for active radiation detection, monitoring and reporting arise within, at the boundaries of, and in the communities surrounding nuclear power, nuclear weapon, and other facilities that utilize radioactive materials both during real-time operation (for monitoring routine releases) and to be present in the event of accidents. Radioactive waste storage and disposal facilities would also benefit from such continuous radiation monitoring. A greater understanding of the dynamics or movements of radionuclides in the environment after release can also be gleaned from information obtained during routine releases as well as for accidents. Such information would be useful for future preparedness planning.
The provision of passive dosimeters from which temporal information may later be derived would also be of great benefit in the area of personnel dosimetry. Because of increasing concerns about tactical nuclear weapons and usage of radiological dispersive devices (RDD) that target troops, inexpensive dosimeters for military personnel who are not usually considered radiation workers are also needed.
While comprehensive screening of cargo and deployment of large radiation detection networks are highly desirable, affordable technology capable of economically performing this function is not yet available. A comprehensive network of radiation detection devices would intercept and monitor the movement of radioactive materials; however affordable technology is not yet available.
The teachings of the present disclosure can also be used for intelligence gathering and other forensic purposes for which it is desirable to determine when or if a given individual or specific item has been exposed to radiation. Retrospective information about the movement of radioactive materials in the environment can, for example, help track a terrorist who set off a dirty bomb or used a portable radiation-producing device to expose a population.
The teachings of the present disclosure may provide utility in connection with the above problems and may also be useful when applied to problems relating to dating geological, archeological, and other samples. Corrections can also be made for retrospective dosimetry using the teachings set forth herein.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.